Colloidal spirals in nematic liquid crystals

TL;DR

This study designs and investigates spiral-shaped colloidal particles in nematic liquid crystals, revealing how their geometry and surface functionalization influence defect structures and enable complex self-assembly behaviors.

Contribution

It introduces novel low-symmetry spiral colloids in nematic hosts and explores their defect configurations and multiple orientational states, advancing understanding of particle-induced defect control.

Findings

Spiral colloids induce diverse director distortions and defect configurations.

Particles exhibit multiple stable and metastable orientations.

Chiral symmetry breaking occurs from achiral particles due to defect winding.

Abstract

One of the central experimental efforts in nematic colloids research aims to explore how the interplay between the geometry of particles along with the accompanying nematic director deformations and defects around them can provide a means of guiding particle self-assembly and controlling the structure of particle-induced defects. In this work, we design, fabricate, and disperse low-symmetry colloidal particles with shapes of spirals, double spirals, and triple spirals in a nematic fluid. These spiral-shaped particles, which are controlled by varying their surface functionalization to provide tangential or perpendicular boundary conditions of the nematic molecular alignment, are found inducing director distortions and defect configurations with non-chiral or chiral symmetry. Colloidal particles also exhibit both stable and metastable multiple orientational states in the nematic host, with a large number of director configurations featuring both singular and solitonic nonsingular topological defects accompanying them, which can result in unusual forms of colloidal self-assembly. Our findings directly demonstrate how the symmetry of particle-generated director configurations can be further lowered, or not, as compared to the low point group symmetry of solid micro-inclusions, depending on the nature of induced defects while satisfying topological constraints. We show that achiral colloidal particles can cause chiral symmetry breaking of elastic distortions, which is driven by complex three-dimensional winding of induced topological line defects and solitons.